Downshifting for a 90 degree turn

No one seems to have noticed that the actual radius of the turn is never mentioned.

A 90 degree turn can be made safely a 70 MPH, or you might need to haul it down to 10 MPH to make it safely.
All depends on the radius.

 

Windsmith, It's the coasting for 5 seconds or so that isn't a good idea. You're not slowing the rig down using the breaking effect of the engine, you're coasting and using the service brakes to slow. That would be considered out of control and an automatic failure on the CDL road test here in VT. Shouldn't be taught in any school.

 

Have to agree on that one...

Had to do my driving test when I came over from Holland 8 years ago. Truck should always be in gear, no coasting allowed.

They also prefered you not to shift during the time making a turn. But that's so hard when you're alredy driving for 25 years, it's sort of automatic thing to do. When doing the test I asked the guy that took the test from me whether he would have me fail for that and he told me that as long as i wouldn't miss a gear and would get it straight back into gear it was no problem. But miss the gear would be a big fail..!!

 

Ahh, that makes sense. In NC 7 seconds is the standard, therefore I assume why it is taught this way here.

 

One country (or two countries in fact...) and so many different rules...

 

No it's scary that your instructors told you to be out of gear for up to 5 seconds at a rip. That by far is the most dangerous thing I've ever heard of an instructor telling a student. You might want to stop by the school and double check to make sure they weren't "f" ing with you when they told you that.

 

A big problem is when you pick up a pre- loaded and sealed trailer. You don't know how its loaded. Today I'm running about 42,000 pounds of paper rolls, but it is loaded very low in the trailer, and they cannot shift. Tomorrow I could be picking up 35,000 pounds of canned food, but it could be stacked to the ceiling. My center of gravity just went to a higher spot in the trailer. I may be a little too fast and aggressive on a particular turn today, and get away with it, but tomorrow I will have to take that corner slower and more gingerly, or end up on the news.

My trainer hated for me to downshift before a turn. He was all jakes and brakes. Get it whoaed down, take the corner slow, then shift after the turn. I'm not saying this is right, but just the way he wanted it.

 

It is bad advice regardless of where it came from. Other than that I will not comment on your instructors experience and advice. The only reason to be out of gear is to be headed efficiently to another gear. Making a planned six gear drop is usually not a wise plan and unless you are braking pretty heavy will take more than 4-5 seconds. When planning a multi-gear downshift a three gear drop is usually entirely manageable without being out of gear too long and a four gear drop not possible in all trucks (Depends on your max RPM's).
Originally you stated:

Try this instead. From tenth gear bring it down to just a tad over idle and go to neutral (So you do not as you said "lug" your engine) . Then raise your RPM's by approximately 3 times the RPM difference between any two gears. If you do not have RPM room to do this, then limit yourself to no more than two gear downshifts. If you have a high RPM engine you may can pull off an efficient 4 gear drop (You need to raise RPM's approximately 4 times the aforementioned RPM difference. BTW, this advice is for level road downshifting .

There are ways to make 4-5 or 6 gear downshifts in a crunch without being out of gear too long, but trust me you are not ready yet!

Best regards.

 

I've known of trainers as well as schools who would not even teach downshifting at all. Shame! Just do it the way you know it should be done, in a controlled manner!

Best regards

 

Only having 1 year experience, my opinion don't mean squat, but I was taught, and practice to this day, that you NEVER let the truck coast. If you are out of gear, you are not in control.

I downshift, from 10 to 8 to 6, once in 6th, I usually go to 4th, then to a stop. Coasting for 5 seconds is bad, not only is it harder to find your next gear, but you are putting unnecessary wear on the brakes.

As far as the turn, I was always taught when turning, no higher than 5th gear, but as low a gear as you need to make it safety.